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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #291129

Title: Use and misuse of antimicrobial drugs in poultry and livestock: Mechanisms of antimicrobial resistance

item Poole, Toni
item Sheffield, Cynthia

Submitted to: Pakistan Veterinary Journal
Publication Type: Review Article
Publication Acceptance Date: 5/17/2013
Publication Date: 7/13/2013
Publication URL:
Citation: Poole, T.L., Sheffield, C.L. 2013. Use and misuse of antimicrobial drugs in poultry and livestock: Mechanisms of antimicrobial resistance. Pakistan Veterinary Journal. 33:266-271.

Interpretive Summary: To maintain a safe food supply, it is necessary to keep animals healthy. In order to do this, antibiotics are often given to poultry and livestock in their feed. In some cases, it is believed that the bacteria that cause disease in humans and animals are becoming increasingly resistant to antibiotics. This has caused public health concerns because diseases once thought largely eradicated are reappearing. Bacteria are not only becoming resistant to one or two antibiotics, they are becoming resistant to many antibiotics; such bacteria are called multi-drug resistant bacteria. In order to find new management practices that would prevent the development and spread of antibiotic resistance, it is necessary to understand what we currently know about how resistance works. It is also necessary to make this information available to people who may be able to contribute further to that line of study because fighting this battle is likely to take decades.

Technical Abstract: Food safety begins on the farm with management practices that contribute to an abundant, safe, and affordable food supply. To attain this goal, antimicrobials have been used in all stages of food animal production in the United States and elsewhere around the world at one time or another. Among food production animals, antimicrobials are used for growth promotion, disease prophylaxis, or disease treatment and are generally administered to the entire flock or herd. Over many decades, bacteria have become resistant to multiple antimicrobial classes in a cumulative manner. Bacteria exhibit a number of well-characterized mechanisms of resistance to antimicrobials that include: 1) modification of the antimicrobial; 2) alteration of the drug target; 3) decreased access of drug to target; and 4) implementation of an alternative metabolic pathway not affected by the drug. The mechanisms of resistance are complex and depend on the type of bacterium involved (e.g. Gram–positive or Gram–negative) and the class of drug. Some bacterial species have accumulated resistance to nearly all antimicrobial classes due to a combination of intrinsic and acquired processes. This has and will continue to lead to clinical failures of antimicrobial treatment in both human and animal medicine.